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Evaluate and appraise a selection of joints from both theeastern and western traditions.
And assess their buildability and performance comparatively
AuthorStudent 100197432011
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Traditional joints
Eastern joints
1 . Kamatsugi
1.2 Koshikake kamatsugi
1.3 Mechigai hozotsuki kamatsugi
2 . Sen2.1 Komisen
2.2 Hanasen
2.3 SHachisen
2.4 Yokosen
2.5 Hiyodorisen
3.Kanawatsugi
3.1 Okkake daisentsugi
3.2 Shachi
3.3 Shippasamitsugi
Western joints
1.Tongue-And-Groove
How to Make Tongue and Groove Joints
1.1 Tongued and Grooved Flooring Board
1.2 Tongued and Grooved Matchboarding
1.2.1 Tongued, Grooved and Beaded
1.2.2 tongued, grooved and veed
1.2.3 Double tongued and grooved
1.2.4 Dovetail Tongue and Groove
1.3 Tongued and Grooved Mitre
2. Birdsmouth joint
How to Cut a Birdsmouth Joint
3. Half joint
How to Make half lap Joints
Different between Eastern and Western joint
Shape and structure
Different in Protection and prestige
Different in Protection sill beam
Different in Construction
Different in Log construction
The function of wood joint
The role of the toolsThe influence of climatic condition
Different in nominate.
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Royal Botanic Garden - John Hope Gateway
Introduction
Building Description
Concept Design
Landscape Description
Inside Description
Structure
Materials
Roof Structure
Stair
Cladding and GlazingFire Resistance and Timber Surface Treatment
Sustainability
Conclusions
Reference, Traditional joints
Reference, Royal Botanic Garden - John Hope Gateway
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1 . Kamatsugi
1.1 A gooseneck tenon and mortisejoint. The mortise is cut into one
section, and the tenon, with head and
neck a single member, is cut into theother. The neck of the tenon is
roughly square or rectagular and
varies in length according to need.
Kamatsugi were used as early as the
7c. By the medieval period (13c-16c),
the head was tapered and resembled
a blunted arrow. A variation
resembling a double gooseneck with
heads at each end of the tenon is set
into the mortise of the same shape.
Usually used to connect two beams.
The joint is called chigiritsugi (Figure 1.1)
1.2 Koshikake kamatsugi
also called shikimen kamatsugi. A half-lap, gooseneck tenon joint. An end joint
which combines two joints: a half-lap koshikaketsugi and a gooseneck tenon
joint kamatsugi. The gooseneck mortise and the bench, or seat, of the lap joint
are cut so that the mortise occupies about half the thickness of the timber.
The bench made from the remaining half extends like a step beyond the
mortise. The second timber contains the gooseneck tenon; the undercut
overlaps the bench when the tenon is dropped into place in the corresponding
mortise. If a half-blind mortise, (mechigai hozoana), is cut vertically into the
center of the bench and a matching tenon is made on the undercut part
beneath the dovetail, the combination joint is called koshiire mechigaitsuki
kamatsugi. The half blind tenon prevents damage from twisting forces.(Figure 1.2)
Figure 1.1 : Chigirtsugi
Note :Spline joints using small pieces of
wood, tenons inserted into the slots,
mortises, cut in corresponding shapes on
the timbers to be joined. The spline derives
its basic shape from combining the narrow
ends of two dovetails. There are various
types, for example, the bow-tie spline
kinekata and the dumbbell spline areigata.
If the splines join timbers parallel to the
grain, the spline is usually lengthenedImage: Kiyos,Seiko
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Koshikake kamatsugiis based
on the same principles as
koshikake aritsugi(Figure 1.2.1 );
only the shape of the tenon and
mortise differ. koshikake
Frequently used to join twohidden purlins (roof joints),
nogeta, and foundation
footings, dodai.
Figure 1.2.1 : koshikake aritsugi
Image: Kiyos,Seiko
Note: A half-lap, dovetailed joint. An endjoint which combines two joints: a half-lap
and a dovetail. The dovetail mortise andthe bench, or seat, of the lap joint are cutso that the mortise occupies about half thethickness of the timber. The bench madefrom the remaining half extends like a stepbeyond the mortise. The second timbercontains the dovetail tenon; the undercutoverlaps the bench when the dovetailtenon is dropped into place in thecorresponding mortise. If a half-blindmortise, mechigai hozoana, is cut vertically
into the center of the bench and amatching tenon is made on the undercutpart beneath the dovetail, it is calledkoshiire mechigaitsuki aritsugi(Figure 1.2.1.1).The half blind tenon prevents damage fromtwisting forces.
Figure 1.2.1.1 : koshiire mechigaitsuki
aritsugi, Image: Kiyos,Seiko
Note: A half-lapped, half-blind, tenoned
dovetail joint. The indented piece is cut
with a bench, lit. hip koshi, open in the
centre to receive the half blind tenon
mechigai. The dovetail and half blind
tenons fit into a dovetail-shaped cavity.
Besides having a half blind tenon, the
tenoned piece also has extended shoulderswhich rest on the benches on each side of
the opening for the blind tenon and the
dovetail. The same principle applies to the
half-lapped, half-blind, tenoned gooseneck
joint mechigaihozotsuki kamatsugi
ogi kubi kama shikimen megi
Figure 1.2 Koshikake kamatsugi,
Image: Kiyos,Seiko
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Figure 1.3 mechigai hozotsuki kamatsugi
Image: Kiyos,Seiko
1.3 Mechigai hozotsuki kamatsugi`corners made by the projection of the neck from the beam.
A blind mortise is cut on the lower half of the matching piece.
The upper sides are adjacent to the gooseneck mortise and are cut away
to form benches koshikake, on either side of the blind mortise.
These fit snugly into the cutaway sides of the blind tenon.
A variation used to further strengthen the joint and prevent twisting
includes right angled blind mortises which may be cut on either side of
the entrance for the neck. Blind tenons are then cut into the matching
piece.
The shape of the joint is visible on top, but from the side, it appears
to be an ordinary splicing joint. This joint is used for purlins andground sills and must have supporting members beneath it.
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2 . Sen
Also called komisen. A pin, peg, key, cotter or dowel made of hardwood,
usually oak. It varies in shape and size depending upon need and placement.
It is added to butt or end joints tsugite, and to angle joints shiguchi, for
strength and security. Holes are bored where necessary and pins are insertedand may pass through tenonned and indented pieces. The sen may be blind
and only partially inserted to prevent slippage. There are many kinds of sen:
2.1 Komisen or daisen. A blindjoint with pins slightly off center.
Komisengama is gooseneck joint
with pins or a mortise-and-tenonjoint used on a penetrating tie beam
nuki. It is characterized by the
addition of a pin or key inserted
through the head of the tenon hozo
into the top of the pillar for purpose
of tightening and strengthening the
joint.(Figure 2.1 Komisen)
Figure 2.1 Komisen
Image : Yasuo,nakahara & paul nii
2.2 Hanasen (lit. nose pin).
A blocking draw pin used in
vernacular houses minka . For
example, a suspended strut
tsurizuka, is joined to a purlin keta.
The end of the transverse beam
hari, in the roof framework is cut
into a large tenon that extends
through and beyond the outer
surface of the pillar. In order to draw
the nose of the beam tightly to the
pillar and to prevent the pin from
penetrating the post or fromslipping, the pin hanasen is cut at
an angle and is driven through a
mortise cut in the extended tenon.
(Figure 2.2 Hanasen)
Figure 2.2 Hanasen
Image : Yasuo,nakahara & paul nii
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Figure 2.4 yokosen
Image : Yasuo,nakahara & paul nii
2.3 SHachisen or shachi
are slightly tapered keys placed in
hunched or right angle mortises
formed by oblique positioning of
matching right angle cuts in both the
tenon and beam. When these parts arejoined, the key's tapered ends are
pounded into the resulting slots. The
slots may be aligned, half or fully
staggered. If two boards are held
together by shachisen, only mortises
are made obliquely, part on each
board, to receive the pin. See (Figure 3.2.1saoshachitsugi), (Figure 3.2.2 saobiki dokko)
2.4 Yokosen
a threshold-to-post pin. This is
driven horizontally into a groove
where the threshold and post meet.(Figure 4.3 yokosen)
2.5 Hiyodorisen
A long cotter with a head,(kashirasen), that passes through
the tail rafters, (odaruki), wherethey meet at right angle on eachside of the hip tail raftersumiodaruki. It protrudes beyondthe rafter on the side opposite itsentry. A small pin called a magosen(lit. grandchild pin) is driven throughthe protruding part to preventslippage and to tighten the pin. It isused in shrine and templearchitecture.(Figure 5.3 hiyodorisen)
Figure 2.5 hiyodorisenImage : Yasuo,nakahara & paul nii
Top (Figure 2.3 SHachisen
Right (Figure 2.3.1 saoshachitsugi),
Bottom (Figure 2.3.2 saobiki dokko).
Image : Yasuo,nakahara & paul nii
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3 Kanawatsugi
An oblique, housed (dadoed), rabbeted,T-shaped, half-blind, tenoned scarfjoint. Because both the tenon andmortise are blind, the joint cannot beslipped together from the side, as in anoblique, housed, rabbeted, scarf jointokkake daisentsugi (Figure 3.1 ). Theoblique surface on the mortised half ofthe indented part is decreased by thedepth of the rabbet. Therefore, the endwith the inverted T-tenon on the
corresponding piece must be insertedin a lengthwise direction. Then a joiningdraw pin komisen is driven through theopening provided in the center to lockthe joints.
Sometimes two keys shachi(Figure 3.2)are used in place of a draw pin tostrengthen the joint.
Figure 3.1 Okkake daisentsugi
Note : An oblique, housed (dadoed) and
rabbeted scarf joint. The upper and
lower pieces are exactly the same but
reversed. The upper part is fitted into
the lower part from the side and two
pins komisen are driven through the two
mortises. The result is a very tight and
stable joint used to join ground sills and
various beams that must withstand
great stress and strain. Okkake tsugiis
identical to okkake daisentsugiexcept
that pins are not inserted. Image: S.Azby
brown
Figure 3.2 Shachi
Note: An abbreviation ofshachisen. A draw pin, key or
cotter made of hard wood, usually zelkova or oak. The
pin is long and thin, with a square or circular cross-
section. It is driven into the upper and lower parts of a
joint, either diagonally or at right angles, to prevent
slippage. Often used to secure joints such as the
saotsugi. Image: S.Azby brown
Figure 3 Kanawatsugi
Image: S.Azby brown
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This joint is commonly used in foundation footings dodai (1) , wall plates
daiwa (2), the beam used for the bottom tracks for sliding doors or window
shikigeta(3) , and in eave purlins dashigeta. The improvement in carpenter's
tools in the Edo period made it possible to fashion complex joints such as this.
Note :
1. Dadoi
A sill, ground sill or footplate. Generally the heavy timber members laid horizontally
at the base of a wooden building upon which pillars or posts are erected. Occasionally, it
is called a sill frame because it forms a grid pattern when laid on all four sides. If ground
sills are provided under wall partitions, they are called partition sills majikiri dodai. In
some small shrine buildings the footplates are laid directly on the ground.2.Daiwa
A wall plate or top plate placed along the top of head-penetrating tie beams or A
circular plate placed on the top of a pillar.
3.Shikiaeta
A beam placed on top of a wall
3.3 Shippasamitsugi
A type of kanawatsugi, a mortised, rabbeted, oblique, spliced joint.
Also called shiribasamitsugi ; obasamitsugi. A blind, stubbed,
housed, rabbeted, oblique, scarf joint. The shippasamijoint has a T-
shaped tenon and mortise and the two members to be joined areslipped in from the side. A pin komisen is inserted into a 15mm
square hole at the center of the joint to hold it securely. The tenon
and mortise are not visible from the sides of the joint but a fine,
straight line is discernible. This is the chief difference between the
shippasamitsugi and the kanawatsugi joint. This joint is used to
connect beams and foundation footings.
Figure 3.3 Shippasamitsugi
Image: S.Azby brown
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its use is in fixing boarding
around an octagonal column of
brickwork. Image: Terrie, Nall
1.Tongue-And-Groove
The tongue and groove joints offer a means of
registering the joint edges during assembly. They are
often used without any glue, allowing the boards to
expand and contract without any negative effects.
The joint is formed by having one piece having a
groove, or slot, cut the length of the edge. This
groove is most often one third of the wood's
thickness and is placed in the centre of the edge,
producing two walls of wood that are the same
thickness. The other piece has the sides of the stock
removed, leaving a tongue that is precisely the width
of the groove formed on the first piece.
The recommended length of the tongue depends on
the width of the stock used to form the panel. For
panels formed with stock less than 3 inches wide,
the tongue length is not that much of a factor. For
these panels, the tongue only needs to be as long as
they are thick. This will produce a tongue thatappears square when viewed from the end. For
panels that are formed with wider stock, it is
recommended that you make the tongue's length at
least half the stock's thickness.
The groove should always be slightly deeper than the
tongue is long, by as much as 1/16" for 3-inch wideboards. The reason for this is two-fold. First is to
prevent problems during assembly. If the tongue
length is cut exactly to the groove depth, then the
slightest piece of sawdust or imperfection in the
wood will keep the two pieces from mating properly.
The second is because of the effects of seasonalexpansion and contraction. If one panel expands at a
slightly different rate than its neighbour, the tongue
from one piece can actually push its neighbour away,
and break the joint.
Note: tongued and grooved
joint suitable for edge or
end jointing, such as fitting
matchboarding round a
chimney breast, making
small jewel drawers, etc.
Image: Terrie, Nall
Figure 1.
Tongue-And-Groove
Image: Terrie, Nall
This figure shows a tongued
and grooved joint with a bead
worked on same to hide the
joint, sometimes called a
staff-bead. It would be usedin positions such as boarding
around an upright iron pillar,
etc., the bead giving a neat
finish at each corner.
Image: Terrie, Nall
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When all the tongue and groove boards in a panel are assembled, there is
often a slight difference in height between the panels, or the panels may
separate slightly due to seasonal changes, and that can produce an effect
that is undesirable for some people. In those cases, you can add a tiny bevel
on the edge of every board. This will produce a v-groove effect between each
board, and it will camouflage the uneven height, at the expense of having avisible groove.
Methods
One of the following woodworking tools may be used to produce the tongue
and groove:
A four- or six-head moulder (for large quantities)
A spindle moulder (wood shaper)
A circular saw bench
Suitable hand planes: a plough plane for the groove and a tongue plane for
the tongue, or a combination plane
A spindle router
A table saw
Where used
The tongue-and-groove joint is often used to form wider panels from
narrower boards, such as when forming table tops, doors, or architectural
panelling. Its also widely used for strip flooring.
Historically, the tongue-and-groove joint was also used to register and align
the edges of vertical panelling in early homes. In this application, the joint
allowed for seasonal expansion and shrinkage of the individual boards whilecreating an airtight wall.
By hand or machine
Historically, the joint was cut with matched wooden planes. These planes
were sold in pairs (in sizes designed to work material ranging from 1/4 in. to
1-1/2 in. in thickness). One plane would cut the groove, and the other would
cut the tongue.
In todays small shop, the tongue-and-groove joint is most often milled with arouter or router table fitted with a pair of matched bits. The matched bits
work much like the old wooden planes, only faster and with less effort. This
joint can also be produced on the table saw
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How to Make Tongue and Groove Joints
Step 1: Cut the Groove
When cutting joints, make sure the router
table is clear of sawdust. The debris under
the wood can cause the cut to be
misaligned. The tongue-and-groove bits are
a matched set. The smaller bit on the right
cuts the groove. The larger bit cuts the
tongue. Washers can be used to adjust the
size of both bits if needed. Put the groove
bit in your router table and set up the cut.
An indexing line on the bit shows you where
the two plates match together so you canlocate the centre of the cut.
Step 2: Cut the Tongue To make the
matching cut, use the bit for cutting the
tongue. This pass removes a large amount
of material, so take it slowly. The two pieces
should fit together to form a nice joint.
Step 3: Use a Straight Flute Bit to Cut the
Joint (Optional)
Specialty tongue-and-groove bits make easy
work of creating the joints, but they can be
a bit expensive. If you dont have the budget
for those bits, a simple straight flute bit can
be used to cut a tongue-and-groove joint.
The same bit can be used to cut both pieces
of the joint. Cut the groove first. Set thefence on the router table so that the bit will
cut approximately through the center of the
board. Turn the board around and make
another pass. The board now has a cut
through the center. For the tongue, move
the fence forward so that youre cutting
away the edges of the board. Your goal is to
leave the same amount of material on the
tongue board as you cut away on the groove
board. This will take at least two passes.
Once the cuts are made, put the boards
together to get a tongue-and-groove joint.All Images: http://woodworkbasic.com
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Figure 1.1 : It is a section of flooring
which is generally made of hardwood,
such as maple, oak, or jarrah. It is
used in positions such as ballroom
and skating rink floors, etc
The tongued and grooved joint is used in one form or another throughout the
whole of the woodworking trades, covering, as it does, a great variety of work
from the laying of flooring boards to the construction of dressers, bookcases
and other cabinet work.
Flooring and match boarding generally have the tongues worked on the solid
board, and examples of a few of the various types are shown as follows:
1.1 : Tongued and Grooved Flooring Board
It used in the construction of floors for mills,
workshops and cottage property. This type of
flooring is nailed to the joists in the ordinary
manner, no attempt being made to concealthe nails used .(Figure 1.1 )
the tongue and groove being worked in such
a manner that the joint covers the nails as
shown. Each nail is driven into its position at
One edge of the board, the groove holding
the next board and hiding the nail (Figure 1.1.1)
1.2 : Tongued and Grooved Matchboarding
1.2.1 Tongued, Grooved and Beaded
It is used for nailing on framing to form
partitions for rooms, etc., for panelling
corridors, etc., and for making framed and
ledged doors, building tool houses, cycle
sheds and other outhouses.
The object of working a bead or beads on
matchboarding is to break the jointing of the
various pieces and to aim at ornamental effect;
also to prevent unsightliness should the timber
shrink slightly. When a moderate amount ofshrinkage takes place, as is nearly always the
case, the joint at the side of the bead appears to
the casual observer to be the fillet or channel
worked at the side of the bead.
Figure 1.1.1 Tongue and groove
joint for nailing
Figure 1.2.1 Tongue and
groove joint with bead
All Images: WILLIAM FAIRHAM
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1.2.2 tongued, grooved and veed
These are used for similar purposes to
Tongued, Grooved and Beaded joint, and
many prefer the V matchboarding variety
because it is more easily painted than the
beaded variety.
1.2.3 Double tongued and grooved
used in the wholesale cabinetfactories. It is preferred for the
jointing of cabinet stock, and the
amateur can make a similar joint by
working two grooves and inserting
loose tongues.
1.2.4 Dovetail Tongue and
Groove
The dovetail tongue tapers
slightly throughout its entire
length, gripping the joint on the
principle of the wedge and
squeezing the glue into the
pores of the wood.
Left : Figure 1.2.4 Dovetail Tongue and
Groove
Top : Figure 1.2.4.1 Double dovetailed
tongue and groove joint
Figure 1.2.2.1 Tongued Grooved and
Veed joint chamfer
Figure 1.2.2.3 Tongued Grooved and
Veed joint radius with bottom
Figure 1.2.2.2 Tongued Grooved
and Veed joint radius
Figure 1.2.3 Double tongued and
grooved joint
All Images: WILLIAM FAIRHAM
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1.3 Tongued and Grooved Mitre
Figure 1.3.1 shows the method ofworking the groove in the above
joints. The pieces are turned back to
back, the mitres thus making a right
angle. The guide on the grooving
plane thus works against each face
of the joint, and this ensures correct
jointing. Figure 1.3.2 is somewhat
similar but with a quarter circlemould to hide the joint.
Figure 1.3 Tongued and Grooved Mitre
Image: Terrie, noll
used for strengthening the corners
of cabinet work, such as tea caddies,
small boxes, plinths, etc. Two pieces
of wood are glued in position andallowed to set prior to glueing and
cramping the joint proper. These
pieces are afterwards planed away,
thus leaving a clear surface to the box
sides.
Figure 1.3.1
Figure 1.3.2
This Figure indicates the building up of a double skirting
mould. C represents the brickwork, A the oak-framed
panelling, and B the packing and fixing block. A wide skirting
of this type is made in two portions for convenience in
working the moulding and to prevent undue shrinkage.
Image: Terrie, noll
Image: Terrie, noll
Ploughing.When grooves have to
be worked in the edge or face of a
board to receive tongues, the process
is generally called ploughing, and it is
usually accomplished by a special tool
called a plough
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2. Birdsmouth joint
In light frame construction, abirdsmouth joint is a woodworkingjoint that is generally used to connect a
roof rafter to the top plate of asupporting wall. It is an indentation cutinto the rafter which consists of a "seatcut" (the face of which rests on the topplate) and a "heel cut" or "plumb cut"(the face of which lies parallel to thesupporting wall), forming a shaperesembling a bird's mouth. Theindentation should not be too deep
(less than a third of the rafter'sthickness) in order to maintain thestructural integrity of the rafter. Thejoint is generally fastened with nails.And it is used a lot for permanentpropping of under purloins in roofs andfor temporary propping in formworkand shoring work.
Figure 2.Birdsmouth jointNote: A birds-mouth joint in a rafter, set
upon a double top plate. Shown are the two
cuts of the joint: the seat cut and the heel
cut.
Figure 2.1.Birdsmouth joint
Note : The sketch above shows the
centre lines of the two members lining
up, and this works in most cases. It is a
good rule of thumb that makes sure that
the small lip is never so small that it can
split off under load and let the prop
slide. Usually fixed with nails in
temporary work
Left : Figure 2.2
birdsmouth joint.
NOTE: It can be
readily made by the
handsaw, used when
a spar fits on the wall
plate. A nail is shown
securing it in position.
Right : Figure 2.3
shows the
birdsmouth joint
where the spar runs
over the outside of
the wall plate, thusallowing a fixing for
an ornamental finish
All Images : William Fairham
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Instructions
1. Angle the blade of yourtable saw at 45 degrees when
you prepare to cut a birdsmouth joint.
2. Position the fence of your table
saw so that the board will be almost
the board's width away when you
cut a birdsmouth joint. This way, you
will save yourself the possibility of
the waste getting trapped between
the board you are cutting and the table
saw's fence.
3. Take your first board and guide it along the fence until you are able to
get the depth you wish. This depth will depend on the thickness of the boards
and the column you are building. You will find that the depth of the blade willmatch the board's thickness.
4 . Repeat the process with the rest of the boards.
5 . Turn the first board over and place it on the table saw.
6 . Adjust the blade downwards about halfway, and adjust the fence of the table
saw of an inch to the left.
7 . Cut the board again, moving the fence to the left as you cut. Continue doing
this until the bottom of the birdsmouth joint, or the bird's beak, is flat.
8 . Continue doing the same with all of the
boards when cutting birdsmouth joints.
Figure 2.5 Adjustable roofing protractor
The tool with particular application to
setting compound angles. The Tool is a 3
dimensional protractor, all the angles are
converted to degrees
How to Cut a Birdsmouth Joint
Figure 2.4 the rafter birds mouth cut
can't be any more than 1/3 the rafter
depth.
Image: Jim rogers
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This figure shows the two components of
the rafter, the main roof triangle, and the
eaves triangle. You need them separated
(mark them separately), to get your birds
mouth line.
If you are fixing timber fascias, leave the
bottom of the rafter uncut, and cut it off
after the roof is finished to a string line.When using a metal fascia with pressed
metal clips that are nailed to the ends of the
rafters, cut your fascia cuts on the ground,
because the clips can take up any small
discrepancies.
Figure 2.6 : Note : Cutting a birdsmouth ona roof depends on the pitch angle of theroof. Looking at the image on the right youcan see a horizontal line drawn above thebirdsmouth cut. The angle between thisline and the face of the rafter (i.e. the topface of the rafter where the roof tiles willbe laid) is the same as the angle at whichthe roof is pitched. Drawing a line 90degrees down from this line gives you thevertical cut which sits at the front of thewall plate. In the case of a 30 degreepitched roof, the angle between thevertical birdsmouth cut and the undersideof the rafter, is 120 degrees.
The purpose ofthe birds mouth is to
allow the rafter to sit easily in the correct
position while fixing. If the rafter was
fixed without a birdsmouth the carpenters
fixing the rafters would have a hard time
stopping them sliding downhill while
nailing them into place.Using metal framing anchors or bolted
connections there is no reason to have
the notch cut out provided that there was
some way of holding the rafters accurately
in position while fixing them. In normal
framed roofs it is a general rule that the
notch should be no more than 1/3rd the depth of the rafter.
All Images: Jim Rogers
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LapJointThere are two categories of lap joints in existence the full and the half
and both of these are used in a slightly different way. The full lap joint is
contrasted from the half-lap in the amount of material that is used to make
the joints. Different types of these joints are used in framing and in cabinetry.
In addition, variations on the joint exist and include the cross, the dovetail,and the mitred.
If two pieces of wood are joined without any material being removed, a
joiner will have made a full lap joint. The thickness of this joint will be the
sum of the thickness of both wood pieces. A full lap requires fasteners in
order to stay together and offers no resistance to racking. However, it does
partly resist twisting and shearing. This joint can be used in temporary
framing and in the construction of some timber frames.
In a half lap joint, material is removed from each of the members so that the
resulting joint is the thickness of the thickest member. Most commonly in
half lap joints, the members are of the same thickness and half the thickness
of each is removed, A half-lap joint can be reinforced by dowels or by
fasteners. It offers some resistance to racking and, when it uses fasteners, to
twisting and shearing.
3 Half joint
A half lap joint is where two pieces of stock, which are typically of the same
thickness, have half of the material removed so that the two boards fit
together so that the joint adds no thickness at the joint. These joints work
well for right-angle connectionsUse for :
Frame assembly in cabinet making
Temporary framing
Some applications in timber frame construction
There are many ways to cut half lap joints and the method employeddepends on the size of the stock. For larger projects where the stock is at
least two inches in either direction, use table saw with a stacked dado set.
For smaller stock, a router table works well.
Figure 3.1 Half lap joint terminology
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How to Make half lap Joints
Step 1: Trace the Lap
Using a pencil, trace the lap on eachpiece of wood. The lap should be half the
thickness of the wood and two to four
times as long as the wood is thick. It's
essential to measure so that the laps on
both pieces of wood have identical
dimensions.
Step 2: Set the Table-Saw Blade
Set a table-saw blade at exactly half the
thickness of the first strip of wood. In this
case, For example if the pieces of wood
are 2" x 4" lumber, whose thickness is
actually 1-1/2", so the saw blade is set at
a height of 3/4".
Step 3: Cut the Wood, and Create an L
Shape
Pass the wood through the blade, starting
at the innermost edge of the lap . Make
as many passes as needed, working the
blade toward the end of the work piece.
Eventually you'll create an L shape in the
wood.
Step 4: Secure the JointRepeat steps 3 and 4 for the second piece
of wood. The two laps should be a
perfect fit. Fasten the joint with glue.
Secure the joint with wood screws.
When to Use Half Lap Joints:
The half-lap joint can be quite strong
when properly used. However, be
advised that thin pieces of stock may be
weakened by removing half of the
material to accommodate the joint, so
use this connection only when the stockis thick enough to maintain the
structural integrity of the board after
half of the material is removed.
All Images :http://www.sawdustalley.co.uk/
http://img.diynetwork.com/DIY/2003/09/18/t163_3fc_lg.jpghttp://img.diynetwork.com/DIY/2003/09/18/t163_3fb_lg.jpghttp://img.diynetwork.com/DIY/2003/09/18/t163_3fa_lg.jpg7/22/2019 Timber Form & Construction 1
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Figure 3.2 : shows the elevation of an imaginary frame which is indicated as made up of
a number of halving joints; it shows also the application of the various joints to this class
of work. Each joint used in the construction of this frame may be dealt with separately.The numbers marked on Fig. 1.2 refer to the individual joints, shown separately in Figs.
1.2.1 to ...
Figrue 3.2.1 :Corner half lap joint(see Figure 3.2, 1). Each piece is halved
and shouldered at opposite sides, thus
forming a perfect fit one with the other
and giving a strong joint with a minimum
amount of labour. For inside work the joint
would be glued. For outside work,, the
alternative method of smearing the joint
with paint or with a mixture of varnish and
white lead would be advisable, the joint
being nailed or screwed.
Figure 3.2.2 T half lap joint
(see Figure 3.2, 2). It may be used in nearly
all cases where a top or bottom rail runs
through an upright.
Figure 3.2.3 Oblique halving joint with
Shoulder
(see Figure 3.2, 3). This type of joint is
used for strengthening framings and shelf
brackets. A strut or rail of this typeprevents movement or distortion to a
frame diagonally.
Figure 3.2.4 Oblique halving joint.(see
Figure 3.2,4) It used in similar positions to
Figure 3.2.3, and has in some cases the
disadvantage of showing end grain at the
top of the frame.
All Images: WILLIAM FAIRHAM
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Figure 3.2.5 Dovetailed Half Lap
Joint.(see Figure 3.2,5)
The dovetailed half-lap improves upon
the design by preventing the lap from
being pulled out due to the dovetail-
shaped lap. To create the joint, first
create the end lap one board and trim
the cheeks to a dovetail shape. Once
done, simply transfer the shape to its
mate and notch it accordingly.
It used in similar positions to Figure
3.2.3, and has in some cases the
disadvantage of showing end grain at
the top of the frame.
Figure 3.2.7 Halved Joint with Double
Dovetail.(see Figure 3.2,7) the pieces at
one end showing a double dovetail. This
particular joint is seldom used except
for Manual Training
Figure 3.2.6 Mitred half lap.(see Figure 3.2,6)
This is a variation of the end lap which shows
a mitre on the face of the finished work.
The mitred half lap is the weakest version of
the joint because of the reduced gluing
surface.
Use for:
Visible framing applications where a mitred
corner is desired
It used in similar positions to Figure 3.2.3,
and has in some cases the disadvantage of
showing end grain at the top of the frame.
Figure 3.2.8 Halved Joint with one sideDovetailed.(see Figure 3.2,8) This joint is
used in similar positions to Figure 3.2.5, and
rather less labour is required in the making.
Figure 3.2.9 Oblique Dovetail Halving.(see Figure 3.2,9) one
side of the piece being dovetailed. The joint is used toprevent racking, and as a cross brace to framing. It is
occasionally made with both its sides dovetailed as shown at
Figu8re 3.2.5.
All Images: WILLIAM FAIRHAM
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Figure 3.2.10 Stopped dovetail half lap
joint
(see figure 3.2,10) In this joint the dovetail
is similar to Figure 3.2.5, with the
exception that it does not run through the
bottom rail. This is an advantage if thebottom edge of the rail is in evidence, or if
it is required to glue a moulding or
hardwood facing slip on the lower edge.
The glue adheres better with the grain
than it would end way of the grain, and if
slight shrinkage occurs across the width of
the bottom rail the moulding would not
be forced away by the upright.
Figure 3.2.11 cross half lap joint. It is
lettered B in Figure 3.2 where each piece
runs through the other.
Figure 3.2.12 shows a Tee Halving Joint
with a dovetail cut on the edge. This is
seldom used except as a woodwork exercise
Figure 3.2.14 Halved joint on barrow wheels
we have the application of halving joints
when constructing a barrow wheel. The
centre portion is an example of three pieces
half-lapped or, as it is sometimes called, one-
third lapped. A sketch of the three pieces
separated is shown at L, B, C, Figure 3.2.14.1.
This joint is extensively used in the pattern
making trade for lap-jointing the arms of
pulley patterns, etc. It is probably the most
difficult of the halving joints to mark out and
construct with the desired degree of
accuracy.
Figure 3.2.13 Halved moulded joint
indicate the halving of cross pieces which
have their edges moulded; the pieces are
shown separately, the moulding being
omitted to give a clearer representation of
the method of construction.
Top Figure 3.2.14
Left Figure 3.2.14.1
All Images: WILLIAM FAIRHAM
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Different between Eastern and Western joint
Shape and structure
Abundance and scarcity of timber
European splicing joints were
seldom as impressive as Japanese
versions. When a carpenter in
Europe went out of his way to
design a new joint, in the 19th
century he had to accept being
ridiculed.
European joints are very simple and
strong rather than Japanese one (left Images), Japanese joints are very
decorative but not strong.(Right
Images)
Japanese carpenters have
traditionally lavished as much
attention on the frames of
their buildings as Westerners
gave to their furniture, partlybecause Japanese shrines and
houses have traditionally had
very little furniture. Before
hand-operated power tools
were introduced to Japan in
1943, the Japanese carpenters
tool chest contained 179
items, mostly wood-workingtools. Japanese and Asian
carpenters tend to saw and
plane towards the body rather
than away from it as Western
carpenters do (the Japanese
method are accuracy than
Western method)and
sometimes maneuver aroundthe outside of tall structures
on poles rather than Western-
style scaffolding.
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Different in Protection and prestige
European timber construction without wooden nails (dowels) would
unthinkable. Every scarf, lap or tenon had to be secured to prevent one part
pulling away from its mate. The wooden dowel, although normally hidden
from view.
Traditional Japanese wood structure have few nails .In juxtaposing Japanese
solutions, the very different artistic attitude of the European is proved by the
dilettantish and often seemingly makeshift nature of protective measure on
building.
Different in Protection sill beam
In Japanese end grain had to be hidden. Unattractive things are hidden, i.e.
denying the presence of any constructional problems, became an
increasingly tantalizing challenge for the Japanese carpenter as exposed
surfaces multiplied. Specifying the aesthetic value of not countenancing any
visible end grain demanded even more refined designs on the eaves corners
than it did on the sill corners, a large properties of which were normally
screened by a column (see frig.1).
At the eaves at least two sides were always completely visible, so joints here
were only permitted to exhibit a mitre seam after assembly (see fig.2).
Fig 1. Eaves corner detailEnjo-ji hondo,Nara,Japan(according to:Bunkazai...,1986,p.348/1)
Fig 2. Eaves corner detailon a hipped roof (accordingto: Graubner,1986,p.132)
Japanese carpenters and architects use their skills not decorate wood
surface but rather to maximize the effect of unadorned wooden surfaces.
Variations are made with different woods, grains and finishes. In Japanese
lumberyards, pieces of wood are not piled in big stacks as they are in
Western lumberyard; rather they are organized by color and grain.
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Different in Construction
The focus on creativity shifted appreciably towards decoration-quite
differently in Japan owing to the aesthetic criteria which different from
those in Europe. The products of this shift in emphasis are judged all too
easily as nonsense by European with their modern sense of values.
The renewal of the bases of columns probably made up the bulk of the
Japanese carpenters workload. This gave him the chance to express his
individuality on a daily basis (see fig.3). The viewer is forced to reflect on the
comparison with the European examples of joints, the functions of which
have been left further and further behind. The age of the frivolous
increasingly takes centre stage (see Fig.4)
Fig 5.
Tranferring the functional parts of a joint to the inside
was in no way abandoned with the coming of the
exclusively decorative features on the surface.-
Sumiya,Kyoto.
In Europe the carpenter proudly displayed his wares,
in Japan the carpenter compelled the viewer to look
more closely(see fig.5)
Fig 3.
Column-base joint on the
lmanishi House in Imai
cho,Nara,Japan
Fig 4. Decorative joints
on the Sumiya,Kyoto.
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The carpenter has connected the pieces in a way which, at first sight,
appears impossible. And that is exactly the effect desired by the joints
creator. His attention having been captured, the observe is normally at a
loss to explain the mystery; every colleagues are puzzled by the
seemingly inexplicable (see fig.6). In this way they achieve a vague
justification for their insubordination with regard to the first rule of
aesthetic, i.e. that the position of the joint should remain hidden from
view.
Such puzzles were not unknown in Europe. So called meister witze
(masters pranks) are impossible joints. What makes them possible
is, on the one hand, knowledge of the materials properties and, on the
other, the ability to break free frame from the chains of conventional
ways of thinking.
What began just above the ground become even more noticeable once
placed at eye level, even for the Japanese, despite their very different
relationship with the ground compared to the people of Europe (Fig.7)
Fig 6.
A decorative joint which requires lateral
thinking to solve the puzzle.-Model of the
Takenaqka-daiku-dogu-kam in Kobe,Japan
Fig 7.
The other two sides of this
gatepost are identical their
visible counterparts.-Osaka-
jo otemon,Hyogo,Japan
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Fig .10 in order to incorporate a
ceiling, for instance, battens to
carry the ceiling can be suspended
in this manner. A member fixed
under the roof construction has a
dovetail end which fits into the
batten. Keys are then inserted into
the batten left and right of thehanger and pushed into place
either side of the dovetail to
secure the batten.
Different in Log construction
In Europe one fundamental problem with logconstruction is that the selfweight of the members canadd up to such a colossal figure that the wall threatensto buckle under the load (see fig.8).
In Japan multitude of joints have been developed whichallow members to be incorporated subsequently (seefigs.9,10).
While wind bracing in Europe was based on fixing theangles between members, attained throughtriangulation, the emphasis in Japan was on the maxim
solid and resilient .this leitmotiv in Japanese column-and-beam construction clearly illustrates the reason whydiagonal brace are encountered comparatively rarely.Only in this way could builders achieve the elasticityrequired to cope with the many earthquakes. Thecarpenters obtained stability by way of the revolutionaryintroduction of the tenon which passed right throughthe column (see fig.11).
Fig .8
Bulgin describes
superbly the buckling
of these logs on the
church in Topola,
Slovakia.
Fig .9 the dovetail of the loose tenon is inserted
into the column and pushed upwards. The rail,
erected afterwards, is now inserted into the
column. The protruding end of the loose tenon
slips into the rail and is held firmly in place by
means of a key.
Fig .11 in Japan it is
specified exactly which
tenon should penetrate
the corner column above
and which below. Oneidentifies the
longitudinal direction ,
the other the transverse.
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When the area enclosed by two horizontal
beams meeting at right-angles was too large,
this area had to be halved by adding a future
beam, It is interesting to observe here to what
extent carpenters remained loyal to theirrespective traditions. In Europe they simply
provided a trimmer to pick up the load from the
extra beam and transfer it back to the two main
beams (see figs.12,13).
In Japan they continued to design tension joints
in the manner to which they were accustomed
(see fig.14).
Fig .14
The carpenters of the Kyuan-ji
romon,Osaka,Japan, first secured the main axis
beyond the usual dimension by means of two
dovetailed rebates in order to secure the otherbeams in the intersection using suitably adapted
dovetails. (According to : Bunkazai..., p.306/1)
Fig .12
As this segment from the
octagonal floor of the
lantern at Ely
Cathedral,Cambridgeshire,E
ngland, illustrates, the
system of providing trimmer
beams was a principle which
was certainly common
throughout Europe.
(According to:
Hewett,1985,Figure.113)
Fig .13 By providing a trimmer
between the main beams,carpenters created space for
fixing an additional beam.-
Granary of Ernstbrunn
Castle,NE A ustria
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The function of wood joint
The function of loadbearing structural wood joint in terms of
construction is to join together pieces of timber permanently and
securely in such a way that the required structural interaction of the
constructional element or the construction itself is enabled. There arevarious ways in which we can reach this goal, as a peculiarity of Japanese
timber construction illustrate superbly. What at first sight distinguishes a
Japanese building from its European equivalent is the almost total
absence of diagonal bracing. This is suspected as being one of the reason
why large buildings too have survived severe earthquakes without
suffering more serious damage. To be able to absorb these destructive
forces has always been one of the prime tasks of Japanese wood joints.
Characteristic of many Japanese joints are the lateral shoulders which
embrace the support; these prevent the horizontal member from
twisting which would seriously endanger such a thin tenon. At the same
time, this partial enclosing of the support seems to be its weak point,
caused by the mortise. The reason for using this type of joint was tooffset the lack of straight building timber and to enable construction with
timber of poorer quality. Only at first sight does this appear to contradict
the enormous volume of wood used in building.
Accuracy of fit was no mere ideal in Japanese building. It was the
absolute minimum requirement for everyday practice. The joints
themselves are the best examples of the interplay: the more branches to
the joint, the more accuracy the carpenter had to work. The reverse of
this is that the carpenter would obviously only invest time and effort in
evermore complicated intersections if his work had a practical objective,
if a real improvement in the joint, with its increasing complexity, could be
expected.
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The role of the tools
For examples dovetail joint linking two parallel log walls, the logs with the
dovetail cut in their end grain are not visible externally. They alternate withthe log with projecting ends. The log walls of which connected in an
astonishingly similar manner to the first Japanese ones but do not exhibit
projecting ends at the corners because they were buried and so did not
require the same secure joints.
In contracts, the pectinate European logs formed, via the joints, a self-
supporting three-dimensional object right from the start, while the Japanese
equivalents, without their vertical retaining supports, would have fallen apart.In Japan it is suspected that saws were used in producing tenon as early as
the 7th century. In Europe the frame saw was not put to use until the end of
the 14th century, from it speeded up or simplified the work. This is probably a
correct assumption for most of those areas in which column-and-beam
construction was common, such construction prevailed in the towns where it
was erected by professional carpenters who had recognized the advantage of
saws much earlier and had already put them into use.
The longitudinal and transverse stiffening of a framework by means of rails
and beams was solved very differently by the Japanese in comparison with
their European colleagues. While the latter often only accomplished their
task through the vertical displacement of horizontal members leading away
from columns, in Japan every effort was made to remain in one place (see
fig.15).
Fig.15 in the Todai-ji nandaimon,Nara,Japan,
the solution in 1199 was to treat each member
equally,all parts being weakend in the same
way.(According to:Zairai koho no kenkyu,1993)
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Kawashima describe very small buildings on the
island of Amami Oshima, Japan, whose exposed
position has been taken into account in their
special construction. Limited by inferior tools,framers used extremely long tenons of reduces
width on their columns, onto which all the
horizontal members, provided with corresponding
holes, were threaded cross-wise. That this type of
construction has proved to be worthwhile might
well be attributable to the flexibility of this tenon
(see fig.16), comparing these with the through-tenons of keyed tenon joints, which were in fact
often assisted by kneebraces but still broke, or the
teazle tenons of the columns, which could not
withstand the thrust of the roof loads, it is
interesting to note just how well the builders of
such structures had to know their material. The
Japanese column tenon was not stronger because it
represented a more sophisticated engineeringdesign. Nor was it more durable because the
timber chosen was more suitable.
.
Fig.16 Koune ke jutaku no
otoshi koho: the principle
of the framing in this
construction in koune
House ,Tokushima,Japan,is
based on threading the
horizontal members onto
the variously tapered endof the loadbearing column.
(source:Tsigu shiguchi
kenchiku no kakusareta
chie,1984, p.51)
The influence of climatic condition
The conditions encountered in Japan are not met with in Europe in the
same way. The traditional Chinese tiled roof, from which the Japanese roof
is derived, weights up to four times that of a modern European roof. The
frequent earthquakes and the typhoons with hurricane-like rainfall
represent a challenge which could not have been tackled by simply using
the unaltered Chinese system. Besides constructional modifications, the
Japanese carpenter also decided to adapt the joints, seen in this right,
statements contrasting the most technically advanced and ingenious
Japanese joints whit those of central Europe, which are weather-resistant
and capable of carrying heavy loads. (In Japan condition such as high load-
carrying capacity were occasionally regarded as being of secondary
importance.)A straightforward comparison is problematic because the condition are so
different.
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For centuries, the Haubarg columns carried theirloads without complaint, so long as their inclinationresisted the thrust of the loads. It was only when thistradition was cast aside and the columns places
vertically that elasticity if the tenon was overtaxed. Ifindividual components of an assembly are altered,whether due to thoughtlessness or lack of expertise,that can lead to apparently inexplicable or wronglyinterpreted consequence.
Column which stand directly on the ground sufferfrom the effect of moisture .Renewal of the column
base is required more frequently than any other partof the construction (see fig.17). In such cases bothEuropean and Japanese carpenters relied on tried-and-tested techniques. In contrast, one conspicuousdifferent between Japanese and European solutionswas the complexity of the joint and itsimplementation (see figs.18,19). Furthermore theclimatic conditions in Japan demanded far more
frequent replacements than in Europe (see fig.20).Some wood joints are made unusable by the weather.The angled jointing nail, for example , was both astrong and widely used method of jointing
Fig .20
Does this stone plinth
the temple gate in
Hagi,Yamaguchi, Japan,
express a sense of
weariness or does its
shape perfectly matched
to the rimber reflect a
hearty joviality ?
Fig .17
Renewing the base of
a post to a simplegrain-drying shed in
Kramsach,Tyrol,Austri
a.
Fig.18 renewedcolumn base on the
Osakajo sakuramon,
Osaka, Japan.
Fig.19 The new columnbase of this grain drying
shed from Carinthia in the
Stubing Open-air
Museum,Austria, appears
primitive by comparison.
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Different in nominate
some Japanese joint have More than one (see
figs.21,22)
The lack of identification in some of the names given to
joints appears excessively liberal. For many Japanese
joints, designate exactly the place at which they are to
be incorporated. While in Europe a long name for a
joint lets us suppose a complicated variant, a similar
conclusion would be totally erroneous in Japan. For
example : Zushi-dodai-sumi-shiguchi tells us absolutely
nothing about the complexity of the connection but
instead solely describes where it is ues: the corner
connection of a sill in a small shrine (see fig.23).
The Japanese carpenter made it his business to not
only produce a joint matched to the respective building
task but to also try out a combination of experience
gained and new ideas in every new building of
significance. Just as the names given to some joints
allow us to discern the purpose for which they wereconceived, the joint receives its final accolade by being
build into the structure: in the first case security against
vertical displacement, in the second horizontal.
.
Fig .22 the secret dovetail corner joint, only
used in Europe by cabinetmakers, is to be
found on many Japanese temples and
shrines. In Japan this joint is variously
called kakushi-ari ( hidden dovetail) and
sumi-tome-ari (mitred corner dovetail).
Fig .21
Both joints are calledari-kake,irrespective
of whether they
interconnect flush or
not.
Fig.23 Sill corner detail
Tomyo-jihondo,Kanagawa, Japan
( according to:
ibid.,p.255/1)
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Introduction
the royal botanic garden, established in 1670 as a physic garden, is now a world-
renowned centre for plant science, research and education. the building has beendesigned by Edward Cullinan. the gateway acts as a threshold to one of the worlds
most important botanical institutions and aims to capture the spirit and enthusiasm
of that organisation.
the building combines the practical need for improved visitor facilities with an
opportunity to engage visitors in the work of RBGE and the exploration of the
relevance of plants to the critical issues of our time. thus, as well as office space, a
restaurant, an outdoor caf, a plant sales area and visitor restrooms, the new centrehouses exhibitions and a studio space for demonstrations and exploration into the
world of plants.
Figure.1 The garden terrace and biodiversity
ponds , Image: Paul Raftry Figure.3 InsideImage: Paul Raftry
Figure.2 Outside
Image: Paul Raftry
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Building DescriptionThe Gateway is set on an important crossing of routes and gives wheelchair access
to the central part of the Garden. Most visitors enter through the double-height
entrance foyer, a dramatic space supported by a diagrid of tapering glulam beams
and framing a view of the Garden beyond. The foyer leads into a large exhibition
space with a fully glazed east wall, 60 metres long, which forms a gentle curve toframe views of the new biodiversity garden. At the centre is a helical timber
staircase set in a rooflit atrium where the diagrid roof is again revealed,
oversailing the open-plan first floor restaurant and extending beyond to shelter
the outdoor terrace of the restaurant.
Rather than a traditional front and back layout, the building can be approached
and entered from several directions and from different levels, through the glazed
and permeable faades. In contrast, the service elements of the building are
enclosed in solid external walls of broken-edged, stacked Caithness slate slabs.
The building is on two storeys with an overall dimension of approximately 100
metres x 50 metres. Spans between columns vary between 8 and 6 metres. It
uses 2750 square metres of cross-laminated timber slabs, 226mm thick on the
first floor and 146mm at roof level.
Figure .6
Image: Paul Raftry
Figure .5
Image: Paul Raftry
Figure. 4
Image: Paul Raftry
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Concept DesignThe pre-eminence of the Garden is the conceptual
driver for the design. The Gateway marks the entrance
to the gardens by facing a road to the west (Figure.8).
On the garden side, stepped biodiversity ponds extend
from the glass wallof the exhibition space and blend into the surrounding
landscape.
The glass wall is some 60 metres long and enables the
message of the interpretation delivered within the
building to be extended into the Garden and vice versa
(Figure.7). At first floor, a roof terrace overlooks the
biodiversity pond and garden (Figure.9).
Given the botanical nature of the building, it was
natural that the structure should use timber
extensively. It uses an innovative combination of glued-
laminated timber and cross-laminated timber for its
walls, floors and roof. Although
timber was considered for the
columns, they are made fromslender fabricated steel
elements.
Figure.9
The garden terrace and biodiversity ponds
(Image: Buro Happold)
Figure.8
The building in context
(Image : Edward Cullinan Architects)
Figure.7 The double-height
entrance is glazed to frame
a view of the garden
beyond.
Image: Paul Raftery
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a major requirement for the design was to reconcile these two uses:visitors were to pass through the building into the garden but also to be drawn
into the interior. Moreover, visitor movement was not simply in one direction: the
westerly John Hope Gateway is not the only entrance to the gardens (the east
entrance) and within the garden the serpentine arrangement of pathways means
that visitors exiting through the new gateway could approach it from north and
south as well as east. Unlike the simple front and back character of a classical
gateway like Stones, this is a building with bulk and with four facades.
The architects response to these complex demands was to make a clear formal
distinction between the gateway and the accommodation. The gateway is
expressed as a glass box, fully glazed on both park and garden sides from ground
to roof, like a greenhouse, through which the eye passes with minimum
obstruction from park to garden and vice versa. The accommodation is expressed
as a solid volume, largely timber-clad and orthogonal on the side facing the park
but cut away on the Garden side to create a biodiversity garden, with the contours
of the land thereby inscribed in the curved shape of the plan. Separating the two,
and marking the direction of travel through the gateway, is a long wall more like
a garden boundary than the face of a building built of Caithness slate in
horizontal strata, which on the park side projects as a tower (albeit only two
storeys high) announcing the entrance. Connecting the two is a floating roof
supported on glulam beams and steel columns, its diagonal geometry offsetting
the orthogonal arrangement of the plan and its clever design and engineering,
allowing a mass of daylight to penetrate via an EFTE rooflight and clerestorey
windows to the space below. When seen from the park this roof is visible only in
the glass box, the glow of top light helping to identify it as the point of entry,
whereas on the Garden side the elevation to the accommodation block is fully
glazed, allowing the roof to appear to hover above an effect that is particularly
pronounced at night.
Figure 10.Section
Image: Buro HappoldLandscape Description
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Once inside the glass box, the visitor has to turn 90 degrees, left or right. Left for the
toilets, contained in a characteristic Cullinan drum, clad in slate and topped by a
smaller drum housing the rainwater collection tank; right for entry to the garden via
the visitor centre. Taking this second route, we step into a double-height galleried
hall, slightly longer and higher than a double cube, flooded with daylight fromabove. At the far end a helical timber staircase beckons, drawing the visitor up to the
first floor. This staircase, 1.5 metres in width but splaying to 2.3 metres as it meets
the ground, is constructed of 164mm-deep horizontal layers of Douglas fir. Whether
or not it is, as the architects believe, the first helical structured veneered lumber
staircase in the world,.
1 Foyer
2 toilets
3 reception4 temporary exhibitions
5 permanent exhibition
6 science studio
7 plant room
8 shop
9 outdoor shop
10, biodiversity pools
11 biodiversity gardens
12 performance space
13 service yard
14 education room
15 offices
16 kitchen
17 restaurant
18 VIP room
19 outdoor classroom
20 external terrace
Figure.11 First floor plan
Image: Buro Happold
Figure.12 Ground floor plan
Image: Buro Happold
Inside Description
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From the top of the staircase visitors can cross the cafe and step straight out onto
a large terrace overlooking the biodiversity garden, or return back down the stairs
and across the double-height hall to re-enter the glass box. Either way, they can
then enter the botanic garden and explore its delights, perhaps exiting after a few
hours by one of the paths leading to the John Hope Gateway from different angles.
Approached from the north, the building reads as not much more than a gardenwall; from the south, it appears much more substantial, with the VIP room on the
first floor projecting under the cantilevered roof, the staff and service entrance
below and the wooden steps of the giant outdoor lecture theatre alongside.
Approaching head-on from the east, it appears long and low, tied into the land by
its reflection in the ponds of the biodiversity garden.
Figure.13 North elevation
Image: Buro Happold
Figure.14 South elevation
Image: Buro Happold
Figure.15 West elevation
Image: Buro Happold
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Structure
Materials
The use of timber
As befits a building in the Botanic Garden, the Gateway is made out of natural
materials with low embodied energy, including a predominantly timber structure.Wherever possible the use of Scottish, then British, then European materials werespecified to minimise transport distances to site.
As the building is designed for long life it was important to use durable and stablematerials. Several types of engineered timber were used in the buildingsconstruction:
Glulam timber, used for the primary and secondary beams to the first floor androof, is European whitewood from Sweden, formed into glulam beams by Cosylvain France, using 45mm thick laminations.
First floor and roof decks are of cross-laminated spruce panels manufactured byKLH in Austria. Exposed partitions are also made of these panels.
Douglas fir structural veneered lumber (SVL) from Germany, supplied by Woodtrade, was used for the mullions and transoms of the timber-framed glazingsystem. To maintain a consistent palette of materials, SVL was also used to
construct the helical staircase and major items of furniture such as the receptiondesk and bar. SVL is made of thin veneers of timber (approx 2mm wide), gluedtogether to form large sheets.
Wherever possible the timber has been exposed, with cross-laminated timberpanels forming the finished surface of the ceilings and exposed walls to publicareas.
Vertically lapped, untreated Scottish larch boards fixed on battens act as a rainscreen cladding system that was designed in consultation with TRADA Technologyto ensure it needs minimal maintenance and easy replacement of the boards. The
lap runs in different directions on three overlapping layers, creating differentshadows that draw the eye along the faade.
The helical staircase continues the horizontally layered emphasis of thebuildings design. It is constructed from SVL sheet, cut and bonded together toform solid treads and curved balustrade, and reinforced with vertical steel bars.The staircase drawing was fed into a CNC machine which laser-cut the SVL sheetinto precise pieces, including the holes for the bars and the handrail (the handrailitself was hand-cut).
Use MDF panel for decorate in restaurant Tables in the restaurant were cut from seasoned logs felled in the Garden itself;they join together to form large composite tables in the evenings.
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Roof Structure
The roof, a single horizontal plane about 100 x 50
metres overall , is supported by a series of deep,
tapered glulam beams on which rest cross-laminated
spruce planks covered with insulation, membrane anda sedum blanket. The glulam beams are laid on the
diagonal and the resulting coffered soffit shapes give
an individual identity to the open plan spaces below.
The beams are supported on pencil-thin steel columns
formed of four steel angles a deliberate strategy, as
the architect explains; We wanted this visually weighty
timber roof to appear as if it is floating. (figure.16)
Figure .16
Cross-laminated panels
Spanning between
Glulam beams
(Image :
Buro Happold)
Figure.17 A view of the tapered
glulam beam roof structure
during construction.
Image: Edward Cullinan
Architects Ltd
Particular features of the roof structure are as follows:
Diagonal grid arrangement
Flitch plates allow moment continuity across the
column head detail
Low stiffness of column leads to small moment
transfer from the beam into the column. By reducing
the bending moment, the use of a slender steel rod is
permitted at the top of the column.
As an equal and large lever arm is provided from the
centre of the beam to each fixing, the annular ring of
dowels resists the bending applied to the beam in a
very efficient manner. It also creates a striking visual
effect when contrasting with the orthogonal
arrangement at first floor level.
Connection design to EC5.
Countersunk bolt detail leads to a loss of section,
which affects the local stress in the timber
Great care was taken to ensure that edge
distances complied with the minimum spacingrequirements of EC5
Due to the column heads
being rather flexible in thehorizontal direction, it was
important to provide a stiff
diaphragm action to transmit
lateral loads to the various
concrete walls and cores,
which carry lateral loads
down to the foundations. The
cross-laminated panels are
screwed into the glulambeams and to adjacent panels
to form these stability
diaphragms at first floor and
roof levels.
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Figure.20
Primary structural
elements
(Image : Edward
Cullinan Architects)
Figure.19
Glulam to Cross-Laminated Panel Detail showing adjustment for
finishes thickness (Image : Buro Happold)
The first floor structure of 226mm thick cross-laminated
(KLH) spruce planks rests on the lower set of glulam
beams, 210 x 815mm deep and set in pairs at 6 metre
grid centres.(fig ure.19 ) To achieve a visually discrete
connection, the beams are bolted to steel flitch plates
welded between the angles of the cruciform steel
columns. (Figures 20 and 21 ). This provides continuity
past the columns to help control deflection of the roof
structure. The connections are carefully tailored to suit
their position in the building; for instance the use of
paired glulam beams allows them to be reinforced with
additional steel flitch plates for special situations,
including cantilever ends and in one location, load
transfer of a column that supports the roof but does not
extend to the ground (to create a column-free space for
the educational studio area).
Figure.18 Before installation,
slots are cut into the ends of
the glulam beams to receive
the flitch plates.
Photo: Edward Cullinan
Architects Ltd
Figure.21 Four glulam
beams connect to a
column head with flitch
plates; the bolts are
arranged in circulargroups to reflect
rotational forces.
Photo: Edward Cullinan
Architects
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At the top of the columns,
steel rods receive the
vertical load from the roof.
In architectural terms, this
rod is the opposite of the
classical capital; ratherthan expressing and
celebrating the connection
between column and
beam, the junction is
visually diminished. Being
on a diagonal grid, the
beams meet at the centre
of the rectangular grid.
The steel flitch plates
which are bolted to the
beams are welded to a
steel bar which provides
moment continuity in the
structure and creates a
strong visual location to
the centre of the coffered
slab. While at first floor
the bolts to the column
flitch plates are arranged
in rectangular groups, at
roof level, for visual
reasons and for structural
efficiency, the bolts are
arranged in circular
groups, providing a strong
visual contrast. The
arrangement also helps
visitors understand the
structure; a circular
arrangement indicates a
rotational force or
movement while a vertical
arrangement indicates a
vertical force or shear.
(figure.22 )
Figure.22 Detail (Image : Edward Cullinan Architects)
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Stair
First there were complaints about the
stairs bouncing as folk walked on them.
Then some wooden supporting pillars
were added to reduce the bouncing.(Figure.25). This of course would increase
the stress loading on the parts of the
stairs closest to the supports. In the
centre of the Figure.26 can be seen a
small bit of white sticky tape
Figure.24 The iron hanger on the left
holding up the top landing is half of the
structural strengthening to stop the
bouncing Image: Paul Raftery
Figure.25 Wooden props were added
to it temporarily while the problem
was considered. It then developed
some cracks in the side wall at a point
of minor inflexion close to a support
point where the stresses would beconcentrated, and was closed to the
public. Image: Paul Raftery
Timber staircase In the atrium makes a
sculptural addition to the space
(Figure.23). It integrated light in an eye-
catching way to accentuate the spiral
form. LED strips of light, embedded intothe timber treads, simultaneously light
both the tops and undersides of the
steps. The effect is of a seamlessly
crafted object.(Figure.24)
Figure.23
(Image : Edward
Cullinan Architects)
Figure.26 crack on stair
(Image : Edward
Cullinan Architects)
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Cladding and Glazing
The glazing system was encloses the building,
whilst maintaining strong expression of the
structure. This was achieved through the
connection of timber mullions to thestructure at the column positions. The glazing
system is by Seufert Niklaus and the SVL
(Structural Veneered Lumber) was supplied
by Woodtrade of Germany. (Figure 27)
The building is clad with vertical boards of
Scottish larch (Larix decidua) sourced from
Russwood timber in the Cairngorms,
shiplapped in a vertical manner. (Figure 28)
Figure .27
Glazing mullions, showing the detailing that
maintains visual expression of the steel
column and timber structure (Image : Buro
Happold)
Figure .28 Larch cladding
(Image : Buro Happold)
Figure.30 Close up of the timber used to clad
the external walls.Image: Edward Cullinan
Architects Ltd
Figure.29 A series of Douglas fir SVL
mullions support the frameless glazing
system. Image: Paul Raftery
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Fire Resistance and Timber Surface Treatment
The timber beams and slabs have inherent charring resistance. The Scottish
Regulations only require that the first floor has a fire rating and no special
measures, other than intumescent paint to the steel structure, were required to
achieve this.In the UK, it is a normal requirement of the regulations that large areas of timber
be treated to achieve a spread-of-flame rating to their underside.
Before specifying the finishes to the timber, the Architects visited projects to
examine weathering, noting that some fire retardant treatments colour the
timber orange after long exposure to UV light. They tested possible finishes
identifying one that would give a good white finish and show grain of the timber.
The following summarises finishes chosen:
INTERNALLY - KLH walls, (stained): Sikkens Cetol stain, then, to achieve class
1 surface spread of flame, Envirograf fire retardant varnish
INTERNALLY - Glulam beams: Buro Happold fire engineers (FEDRA) prepared
a Technical Justification Report, which was accepted by the building control
approval body, after discussions with the Scottish Fire & Rescue Advisory Unit.
This showed the fire (flame-spread) treatment to the Glulam beams to be
unnecessary.
EXTERNALLY- KLH soffit: Clear Sadolin quick drying wood preservative, and
top coats Sikkens Cetol white stain
EXTERNALLY- Glulam beams under soffit (clear): All of the external glulams
were treated with externally suitable, clear treatment of Dulux Weathershield
Naked Wood.
EXTERNALLY- Glulam edge beams (white & clear): As these beams receivemore UV/weathering, The Architect specified a stain (the same finish as the
external KLH external soffit shown above).
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Sustainability
A sustainable, low-energy, minimum-waste approach to the buildings design was
part of the message the Garden wished to convey to its visitors. The Gateway has
many demonstrable environmental solutions including the extensive use of
timber; they include a biomass boiler, a green roof, rainwater harvesting, a wind
turbine, photovoltaics (include 11m2 photovoltaic array,), solar collectors for hot
water(15m2 solar thermal panels), natural ventilation and passive night-time
cooling. The sedum roof reduces heat gain to the building in summer, slows down
rainwater run-off and provides an extra blanket of insulation. The design of all
these elements is explained in the permanent exhibition on the ground floor of
the Gateway and this engagement with the public is an important contribution to
the project.
The building is kitted out with all the standard eco-devices and features. But more
importantly it uses materials that are appropriate to its location, especially timber
in various forms, for both structure and finishes. Above all it feels like a building
that belongs to its site and purpose. Some may feel that the device of the glass
box is made to work too hard, with the expectation set up by the eye not being
borne out by experience, but this is countered by the sheer delight of the
architectural promenade thereby established. By careful attention to site,
topography and materials Edward Cullinan Architects has created a building thatwill adorn the city.
Exterior lighting
Outdoors, the rough slate walls are uplit to reveal their stony texture with deep
shadows and highlights. The exterior lighting was carefully focussed to minimise
light pollution important in an area of unspoiled natural beauty. Energy-saving
controls and sensors are also used throughout the project.
The main entrance lobby is an unheated buffer space with abundant daylight for
the plants. Services for heating, hot water and power are hidden underneath the
slab with more service routes integrated at high level.
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Turbine
the wind turbine can produce, at peak, 6 kw of energy, and
contribute to the power supplying the building.
That will contribute the intermittent power supply of about
twelve 100 watt lightbulbs.(Figure.33)
This building has extended its 70 acres of
spectacular greenery with 1400m of plantsexpertly installed at roof level - the crowning glory
for a new visitor centre.
The project was completed using the versatile
Diadem green roofing system and Alwitra single ply
waterproofing membranes supplied by ICB
(International Construction Bureau) Ltd, the UKs
leading supplier of sustainable roofing. Completed
in June 2009, it offers a long lasting and eco-friendlycover for the 15.7 million development.(Figure.32)
Royal Botanic Garden, is the world renowned centre
for understanding, protecting and preserving plants
for a sustainable future. (Figure.31)
Figure.31 The sedum roofprovides
natural insulation for the
building. Image: paul Rftery
Figure.32 Green roof Image: Buro Happold
Figure.33 Turbine
Image: Buro Happold
The Gateways roof will aid the environment
in a variety of ways, stimulating local
biodiversity and oxygenating the air. It will
also help to combat climate change by
providing natural air conditioning - the earth
roof cools the building in summer andprovides high grade insulation in winter. This
also lessens the impact of thermal shock on
the structure and other forms of stress on the
roof.
As well as controlling temperature, the soil
reduces the need for drainage by absorbing
rainwater, minimising harmful runoff andlimiting the risk of water damage to the
building.
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The Gateway has many demonstrable environmental solutions including the
extensive use of timber; they include a biomass boiler, a green roof, rainwater
harvesting, a wind turbine, photovoltaics (include 11m2 photovoltaic array,),
solar collectors for hot water(15m2 solar thermal panels), natural ventilation
and passive night-time cooling. The sedum roof reduces heat gain to the
building in summer, slows down rainwater run-off and provides an extra blanket
of insulation. The Gateway is predicted to achieve Rating A on its Energy
Performance Certificate.
Conclusions
A clear concept remained a consistent driver of design from the competition
through to the completion of the building. However it was hard to maintain this
clarity. Many of the details appear to be simple, but the variations in a building
of this shape, which is moulded to fit the contours of the landscape of the site,lead to many permutations of the standard details.
The final building maintains clarity in the expression of the structure,
particularly in the use of timber. Success in projects of this type can only be
achieved by close integrated working of the design team with the Client,
contractor and specialist sub-contractors.
Given the botanical nature of the buiding, it was natural that the structure
should use timber extensively. It uses an innovative combination of glued-
laminated timber and cross-laminated timber for its walls, floors and roof.
Although timber was considered for the columns, they are made from
slender fabricated steel elements.
visitors can pass through the building into the garden but also to be drawn
into the interior. Moreover, visitor movement was not simply in one
direction: the westerly John Hope Gateway is not the only entrance to the
gardens (the east entrance) and within the garden the serpentine
arrangement of pathways means that visitors exiting through the new
gateway could approach it from north and south as well as east.
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Reference, Traditional joints
1.Klaus Zwerger, wood and wood joints-building traditions of European
and Japanese, Birkhause publishers for architecture .Basel. Berlin.
Boston.ISBN 3-7643-6333-9
2.William Fairham, The Wood workers Series- Wood works joint,
Philadelphia and London J. B. Lippincott Company, 1921
3.William Fairham, The Wood workers Series- Wood turning,
Philadelphia and London J. B. Lippincott Company, 1921
4.Gary Rogouski, The complete illustrated guide to joinery, Distributed by
publishers group West. 2002
5.Terrie Noll, The joint book-The complete guide to wood joinery, Chart
well book, 2006
6. Terrie Noll ,The Encyclopedia of Joints & Jointmaking, RD Press
publication, 1997
7.Richard Harris, Discovering Timber-framed building, Shire publications
LID. ISBN 0 74780215 1
8.Kiyos Seiko, The art of Japanese Joinery, Weatherhill publication, 198
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